Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dau tren » dau tien, dat tren, dau tieng
su sach » so sach, vu sach
van cam » van nam, van lam, van cau
va hanh » van hanh, va thanh, va danh
du tren » dua tren, duc tren, tu tren
y nang » ky nang, ly nang, v nang
xuc va » duc va, tuc va, luc va
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang ((x hoi) or (o hoi)). hieu van cam xuc va hanh vi ((du tren) OR (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang ((x hoi) OR (o hoi)). hieu van cam xuc va hanh vi ((du tren) OR (dau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang ((x hoi) or (o hoi)). hieu van cam xuc va hanh vi ((du tren) OR (dau tren))".
• Adding a wildcard symbol may retrieve word variants: su sach y nang ((x hoi) or (o hoi)). hieu van cam xuc va hanh vi ((du tren) OR (dau tren))*.